Jetta 88 problem

Hello, how are I from Mexico DF and I have a problem with a Jetta 88, the car starts perfect but when you release the accelerator and when you start it for the first time it stays well for a while after about 20 25 minutes already in the failure of the fault and in all day the accelerator is released and I do not find the fault, I can help me send the carburetor to clean. Carburetor, I don't know what else to do.

I appreciate your help

It is something of the idle; so when you release the accelerator pedal stops.
It is advisable to clean the accelerator set, which you already did so you can find the air sensor of the fuel and check distributor if it is working well.

Verify the sleeve that goes from the multiple of admission to the servo-freans usually take a breath.
I hope it serves you greetings from Tenerife

Thank you for your tips the problem was solved, the carburetor spare was cleaned and changed